Perpendicular recording medium in current hard disk applies a recording layer having a composition containing oxide such as CoCrPt—SiO2 or CoCrPt—TiO2. In the future, the perpendicular recording medium is expected to have a multilayer-film structure such as Fe/Pt or Co/Pt which is a High-Ku material.
Under a condition of ensuring the maintenance cycle of one week or longer, however, there is required to have cathode units by the number of the layers in order to fabricate the multilayer-film structure.
A structural example of the sputtering apparatus for forming such a multilayer film is disclosed in Patent Document 1, which is illustrated in FIGS. 5A to 5C and FIG. 6. Outline of the structure is described below.
FIG. 5A is a schematic drawing of a cross-sectional structure perpendicular to the substrate-carrying direction, of a sputtering chamber 101. As illustrated in FIG. 5A, a rotary cathode unit 103 is rotatably mounted to each of the two side-walls of the sputtering chamber 101. Discharge is generated on both sides of a carrier unit 102 which holds two sheets of substrates 122, and thus laminated films are simultaneously formed on both sides of the two sheets of substrates 122.
As illustrated in FIG. 5B, each of the substrates 122 is held by the carrier 102 by three (for example) supporting claws 121, and the carrier 102 is then transferred to the respective treatment chambers by a known transfer mechanism.
FIG. 5C is plan view of the rotary cathode unit 103 viewed from the substrate 122 side. As illustrated in FIG. 5C, the rotary cathode unit 103 is provided with a CoB target 132, a Pd target 133, and a lamp heater (heat-treatment mechanism) 134 to heat the substrate 122, which are arranged on the same circumference with respect to the rotational center. A partition 131 is positioned between the target 132, the target 133, and the lamp heater 134, respectively, to prevent interference therebetween and to prevent contamination thereeach.
FIG. 6 is the A-A′ section of FIG. 5C to describe detail structure and detail mechanism of the rotary cathode unit 103.
In the conventional sputtering apparatus illustrated in FIG. 6, at least one surface-treatment mechanism (the lamp heater 134 in FIG. 6) for the target 132, the target 133, and the substrate 122 is installed around a rotary shaft 130 of the rotary cathode unit 103. A substrate holder (the carrier 102) which holds one or more of substrate 122 is positioned so as to face the target 132, the target 133, and the lamp heater 134, and thus the rotary shaft 130 or the substrate holder is configured to be rotated. At a step part of a cylindrical outer frame 140 at rear-face side of the targets 132 and 133, there is positioned a magnet unit having a center magnet 141, a peripheral magnet 142, and a yoke 143. A center shaft 145 of the magnet unit is rotatably supported by a bearing 146. In addition, a gear 144 is mounted on the bottom surface of the yoke 143, and the gear 144 engages with a gear 119 located at front end of a cylinder member 116 positioned between the cylindrical outer frame 140 and the rotary shaft 130. As a result, rotation of a motor 117 induces the rotation of the cylindrical outer frame 140 via the gears 118 and 147, (or induces revolution of the targets 132 and 133 and the magnet unit centering on the rotary shaft 130), further induces rotation of the magnet unit via the gears 119 and 144. The cylinder member 116 is fixed to the rotary shaft 130 and the cylindrical outer frame 140 via a bearing 148.
According to the sputtering apparatus of FIG. 6, the sputtering is carried out while rotating the magnet unit. By, however, shifting the center of the center magnet 141 from the center of the center shaft 145, the sputtering apparatus is configured so as to prevent the formation of non-erosion region at the center of the target 132 and the target 133.
Another structural example of multilayer-film forming apparatus in related art is disclosed in Patent Document 2 as illustrated in FIG. 10 and FIG. 11. Outline of the apparatus will be given below.
In the multilayer-film forming apparatus illustrated in FIG. 10, a first cathode 1001 and a second cathode 1002 providing the first target 1001a and the second target 1002b, respectively, around the center shaft are arranged. FIGS. 11A to 11D illustrate the arrangement and the shape of pluralities of targets in the multilayer-film forming apparatus of FIG. 10. A substrate 1003 is supported by a supporting member 1004 by facing the first cathode 1001 and the second cathode 1002. In the multilayer-film forming apparatus of FIG. 10 and FIGS. 11A to 11D, when forming a multilayer film on the substrate 1003, films of the target materials of the first target 1001a and the second target 1002a are formed in a spiral manner on the substrate 1003 while rotating the first cathode 1001 and the second cathode 1002 around the center shaft.